Blue arse fly

n.

Heard in Tipperary, Dublin and Waterford

A bluebottle fly, or to move about frantically; also to become excited or angry.

In use

Yer in early paddy, be gor I am, herseff was goin round like a blue arse fly this mornin, so I had ta leggid.

Posh English

You have arrived early, Paddy. By Jove I have. Her good self was scurrying about like a frenzied bluebottle this morning, so I was obliged to depart without delay.

Same phrase, other counties